1. Spacing between patchs
The spacing between the patchs is neither too large (waste circuit layout), and it is not too small to avoid solder paste printing and difficulties in welding.
The spacing can refer to the following specification:
■ The same device: ≥ 0.3mm
■ Different devices: ≥ 0.13 × h + 0.3mm (H is the maximum height of the surrounding neighbor and device)
■ When handwelling and patch, the distance between the device is required: ≥ 1.5mm.
2, the distance between the direct insert and the patch
As shown in the figure above, the in-line resistance device and the patch should be kept enough, it is recommended to be between 1-3mm, because of the trouble of processing, it is now rare. However, the board external socket is often a direct plugin.
3, the placement of the decoupling capacitor of IC
The decoupling capacitance needs to be placed near each IC's power port, and the position is as close as possible to the power port of the IC. When a chip has a plurality of power ports, each interface is arranged to arrange decoupling capacitance.
4, the direction of the components along the PCB edges and distances
Since it is generally used to use a puzzle to do PCB, the devices near the edge need to meet two conditions.
The first is parallel to the cutting direction (uniform mechanical stress of the device, such as if it is placed in the way to the left of the above figure, the two pads of the patch may be different when the patch is split. Dispel off)
The second is to arrange the device within a certain distance (damage to the components when the board is cut)
5. Contact adjacent pads
If the adjacent pads need to be connected, first confirm that the connection is performed outside, preventing a group from causing bridging while paying attention to the width of the copper wire at this time.
6, padding falling in the area
If the pad falls in the paving area to connect the pad and pave, according to the current size, it is determined whether it is connected to 1 line or 4 heel.
If the left side is taken, it is difficult to welding or repair the components, because the temperature through the copper is fully dispersed, the temperature is difficult.
7, pad teardrop
If the wire is smaller than the pads of the insertion device, you need to tear the way to the left.
The tears have the following benefits:
(1) Avoid removal of the signal line width and cause reflection, which can make the connection between the trace and the member pad tend to transition.
(2) Solve the connection between the pads and the traces to break the impact force.
(3) Set tear drops can also make the PCB board more beautiful.
8, the components lead width
9, keep not using a lead pad
For example, one chip is the case where two pins are not used, but the chip real pin exists. If the two-pin feet are in the right side of the figure, it is easy to cause interference.
If the chip pin belongs inside the unconnected (NC), plus the pads on the pad can avoid interference.
10, avoid the opening of the pad on the pad
11, wires and PCB board edge distance
Note that leads or components cannot be passed through near, in particular single-sided panels, and the general single panels are mostly paper panels, and they are easily broken after the force, and if they are on the edges or amplifiers.
12, electrolytic capacitance away from heat source
First, consider whether the ambient temperature of the electrolytic capacitance meets the requirements, followed by so far away from the heat generating area as much as possible to prevent the liquid electrolyte inside the electrolytic capacitor to be baked.
Original title: 12 details of PCB board Layout
Article Source: [WeChat public number: FPGA Getting Started] Welcome to add attention! Please indicate the source of the article.
Editor in charge: Haq, Read full article, original title: 12 details of PCB board Layout
Article Source: [Micro Signal: xiaojiaoyafpga, WeChat public number: e-wood] Welcome to add attention! Please indicate the source of the article.
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